Dynamic speaker having dome diaphragm and basket frequency

ABSTRACT

An all-frequency loudspeaker of the type using a voice coil suspended in a magnetic field and driven by the usual audio transformer of an amplifier system. The inventor&#39;&#39;s contribution lies primarily in substituting for the usual paper cone diaphragm of the prior art an outwardly convex metal diaphragm secured near its center to an extension of the form or tube on which the voice coil is wound. As with other diaphragms, the convex metal diaphragm is secured to the rigid framework of the system by a resilient suspension at its outer periphery. A second resilient suspension extends between the framework and that part of the coil form adjacent the coil. Also disclosed is a combination of the improved speaker with a hard surfaced, spherical shell enclosure. When using the enclosure, a section of it is removed and the speaker is mounted in the opening so that the spherical wall of the enclosure is interposed between the outwardly convex diaphragm of the speaker and its voice coil. This effectively isolates and nullifies the sound produced by the back of the speaker as the diaphragm moves backwardly, leaving only the sound produced by the front of the diaphragm to reach the listener.

United States Patent 1 1 1 1 3,925,626 Stallings, Jr. Dec. 9, 1975 [54]DYNAMIC SPEAKER HAVING DOME [57] ABSTRACT DIAPHRAGM AND BASKET FRAME 6 tAn all-frequency loudspeaker of the type usmg a voice [7 1 InventorRobert John Staumgs BOX coil suspended in a magnetic field and driven bythe 230, Sugafland 77478 usual audio transformer of an amplifier system.The [22] Fil d; F b. 22 1974 inventors contribution lies primarily insubstituting for the usual paper cone diaphragm of the prior art an [21]Appl 444,825 outwardly convex metal diaphragm secured near its center toan extension of the form or tube on which [52] us CL 179/1 5 5 179 5181/153; the voice coil is wound. As with other diaphragms, the

181/172 convex metal diaphragm is secured to the rigid frame- 51 Int.c1. H04R 9/06; H04R 1/02 Work of the System y a resilient Suspension atits [58] Field of Search 179/1155 R, 115.5 vc, outer Periphery A secondresilient Suspension extends 179/181 R 1155 s 15 7 171, between theframework and that part of the coil form 157 17 adjacent the coil. tAlso disclosed is a combination of the improved [56] References Citedspeaker with a hard surfaced, spherical shell UNITED STATES PATENTSenclosure. When using the enclosure, a section of it is 2,187,236 1/1940Hausdorf 179/115.5 R removed and the Speaker is mounted in the Openingso 2,405,179 8/1946 Black, Jr. et al 179/115.5 R that the Spherical WallOf the enclosure is interposed 2,442,791 6/1948 Wente 179/181 R betweenthe outwardly Convex diaphragm 0f the 2,509,224 5/1950 Gayford 179/115,5R speaker and its voice coil. This effectively isolates and 2,942,0716/1960 Witchey 181/171 nullifies the sound produced by the back of the,014,996 12/1961 Swanson" l79/115.5 VC speaker as the diaphragm movesbackwardly, leaving 3,026,955 3/1962 W1lber 181/153 only the Soundproduced by the front of the diaphragm to reach the listener. PrimaryExammer-Kathleen H. Claffy Assistant Examiner-George G. Stellar 6Claims, 4 Drawing Figures Attorney, Agent, or FzrmRoy H. Smith, Jr.

US. Patent Dec. 9, 1975 Sheet 1 of 2 3,925,626

* f igi US. Patent Dec. 9, 1975 Sheet 2 of2 DYNAMIC SPEAKER HAVING DOMEDIAPHRAGM AND BASKET FRAME FIELD OF THE INVENTION The present inventionis converned with improvements to direct radiating dynamic loudspeakers,in particular those utilizing a voice coil suspended in a magnetic fieldand driving a diaphragm to change the audio frequency currents in thevoice coil to audible sound waves radiating from the diaphragm. Morespecifically, the invention is concerned with novel combinations ofdiaphragms and the means linking such diaphragms to the voice coil,novel means for suspending the linking means to the framework, suchsuspension having lead wires secured therein, and novel combinations ofthe improved speakers with speaker enclosures. Such improvements areapplicable to a wide range of sizes of loudspeakers, suitable for usewith all audio frequencres.

PRIOR ART None of the improvements of the present applicant is known tobe commercially available. Except for the high range of frequencies, theloudspeakers that are available still use the familiar paper conediaphragm and, as resilient suspensions for the cone, corrugated membersmade of various materials such as textile fabrics, sometimes impregnatedwith a resin or plastic. It is still the standard practice to run thelead wires through holes in the conical part of the metal framework,thence through the paper cone and down along the surface of the cone tothe voice coil. Such lead wires are generally left slack, and the resultis that they vibrate as the cone vibrates, an action known as wire slap.This sometimes becomes so troublesome that the lead wires fail infatigue, and other times they puncture the cone and cause it to rattle,a phenomenon known as cone break-up.

The commercially available enclosures for speakers are still limited tothose having six or more fiat sides, and many such enclosures includeboth a large diameter speaker for low frequencies known as a woofer anda small diameter speaker for high frequencies, a tweeter, both mountedon flat walls. Such enclosureloudspeaker combinations do not give afaithful reproduction of the original sound, but tend to distort thesame, to introduce undesirable harmonics, and are prone to be highlydirectional.

With respect to patented and otherwise published prior art, somewhatmore is known. The superiority of spherical enclosures, for instance,was disclosed by Harry F. Olson in his article Direct RadiatorLoudspeaker Enclosures, published on pp. 2229 of The Journal of theAudio Engineering Society, Vol. 17, No. 1, January, 1969 althoughlimited to work with speakers utilizing only paper cone diaphragms.Other relevant art appears in Hamsons US. Pat. No. 3,032,615 (May 1,1962), disclosing the use of silicone grease to stick lead-in wires to asuspension, and Villchurs US. Pat. No. 3,033,945 (May 8, 1962),disclosing the use of a domed diaphragm for tweeters made of a phenolicimpregnated fabric. Villchur teaches the use of only a single resilientsuspension, and secures his voice coil directly to the outermost rim ofhis domed diaphragm. While this may work fairly well for tweeters, whichare only l-2 inches in diameter, it has not been proven feasible forlarger diaphragms, from 2 /2 to 6 inches in diameter.

OBJECTS OF THE INVENTION Accordingly, the principal object of thepresent invention is to provide a dynamic loudspeaker which may be usedto obtain high fidelity sound. A second object is to provide such aloudspeaker in combination with a spherical enclosure to furthermaximize the fidelity of the reproduced sound. A third object is tofurnish in such loudspeaker a novel combination of an outwardly convexdiaphragm and means linking such diaphragm to the tube or form on whichthe voice coil of the loudspeaker is tightly wound and secured. A fourthobject is to provide a loudspeaker having an improved means of mountingthe lead wires to the voice coil, one which avoids the wire slap ofprior art loudspeakers. A fifth object is to provide a novel combinationof loudspeaker elements so structurally interrelated that the diaphragmreciprocates as an entity and there are few or no vibrations in only apart of the diaphragm. A sixth object is to furnish such loudspeakersand loudspeakerenclosure combinations which may be used in a single sizeto faithfully reproduce all frequencies present in the original sound. Aseventh object is to provide a loudspeaker which will faithfullyreproduce all audio frequencies. An eighth object is to provide betterhigh frequency dispersion and phase characteristics in suchloudspeakers.

SHORT STATEMENT OF THE INVENTION The above and further objects arerealized according to the concept of the present inventor by utilizingan outwardly convex diaphragm, e.g., a thin spherical shell, preferablyof metal. The convex diaphragm is secured to the voice coil by extendingthe tube or form on which the voice coil is tightly wound and secureduntil the tube contacts the diaphragm, and integrating the tube end tothe diaphragm by adhesives or other suitable securing means. Anysuitable magnetic structure may be utilized, with the voice coilsuspended in the air gap of the magnetic circuit. Customary means areused to form a resilient suspension connecting the outer periphery ofthe convex diaphragm to the framework of the loudspeaker, but a somewhatdifferent and improved suspension is used to secure the extended tube ofthe voice coil to the framework. While the second suspension is still aresilient suspension, it is made of a virtually flat woven cloth and hasthe lead wires for the voice coil woven into it, wrinkled in assembly toprovide the slack necessary for axial movement.

Such a speaker is preferably mounted in a spherical enclosure to obtainthe maximum advantage from it.

SHORT DESCRIPTION OF THE DRAWING FIGURES The invention is probably moreeasily comprehended by reference to the accompanying drawing, readtogether with the details below. In the drawing:

FIG. 1 is an exploded perspective view of a particular embodiment of theimproved loudspeaker of the invention;

FIG. 2 is a cross section of an assembly of the same embodiment, withthe addition of connectors and insulators for the lead wires;

FIG. 3 is a cross section like that of FIG. 2 but using a differentmagnetic structure, and

FIG. 4 is'a cross section of a combination of the loudspeaker of FIG. 3with a spherical enclosure.

DETAILED DESCRIPTION OF THE DRAWING FIGURES The loudspeaker illustratedin FIGS. 1 and 2 includes a more or less conventional framework 11 whichincludes a sidewall 12 joined to a horizontal base 13 extending inwardlytoward its axis of symmetry 42. At its upper edge the sidewall 12 isjoined to an outwardly jutting inner flange 43, which in turn is joinedby a short sidewall 45 to an out-turned mounting flange 44. This flange44 may be square, as illustrated, or any other convenient shape. It isalso convenient to provide it with a number of mounting holes 48. Thesidewall 12 (not necessarily conical, as shown) is preferably providedwith a number of vents 46, most importantly in order to permitcompressions and rarefactions of the air behind the diaphragm 34 tocommunicate with the surrounding air. Vents 46 also provide a convenientmeans for passing the voice coil lead wires 28 and 30 through theframework.

Base 13 of the framework is firmly secured to the top surface of themagnet structure comprising pole piece 14, bottom plate 16, center ring18 and top ring 20, all of which are firmly secured together without airgaps except the gap 22 between the inner circumference of top ring andpole piece 14. The through opening 17 in pole piece 14 and bottom ring16 is an optional feature which is believed to produce somewhat superiorperformance. The reason for this is analogous to the reason for vents46, as opening 17 provides a connection between the air space overlyingpole piece 14 and the surrounding air, permitting the air which isvariously compressed and expanded to attenuate such changes into theatmosphere. (There is an alternate but more restricted path through airgap 22.)

Mounted on the inner flange 43 of the framework by means of resilientmounting 38 is a spherical or domed diaphragm 34. Diaphragm 34 ispreferably made of a quite thin sheet metal, e.g., aluminum in athickness of about 0.01 inch. The thickness should be the minimumconsistent with rigidity, as it is desirable that the diaphragmtranslate up and down as a whole, without any part thereof vibrating ata different rate and without lagging behind or leading the balance ofthe diaphragm. This thickness will naturally vary with the metal orother rigid material employed.

The surround or resilient suspension 38 is more or less conventional,and is tightly secured to both the framework flange 43 and the outerperiphery of diaphragm 34. Typically, it is a dished or corrugated ringof fabric impregnated with a plastic to add some rigidity; thecorrugations or concavity help supply the proper degree of rigidity andat the same time permit the mounting to be stretched as necessary toaccommodate up and down movement of diaphragm 34.

Tightly secured to the underside of diaphragm 34 by an adhesive or othersuitable connection 36 is the tube or form 32 which is centered on theaxis of symmetry 42 and extends downwardly into the air gap 22. Also inthe air gap and tightly wound on the lower portion of form 32 is thevoice coil 24. Voice coil 24 is made of an appropriate wire gauge andwith an appropriate number of turns so that the currents passing throughit will react with the magnetic force in the field passing through airgap 22 to cause a force upward or downward from the coil, in thewell-known manner.

Form 32 is partially supported in air gap 22 by a lower resilientsupport 40. This lower support 40 is tightly secured at one end to theform and is tightly secured at its other end to the inner end of base 13of the framework. While resilient support 40 is similar in its action tothe upper resilient support 38, it differs therefrom in that it is madeof essentially a flat piece of cloth which is wrinkled in assembly forthe up and down motion of the form 32.

The lower resilient support 40 also differs from previously known suchsupports in that it includes the leads 29 and 31 from the pair of endsof voice coil 24. Such leads 29 and 31 are preferably actually woveninto the fabric of support 40, and are provided at their outer ends withmetallic connectors 26 which are soldered or otherwise electrically andmechanically connected to the wire ends of the leads 29 and 31. Sincethese connectors immediately adjoin the metallic framework member 13, itis preferable to secure under each lead or each connector 26 aninsulating wafer 27, to avoid short circuits. Each connector 26 is thenconnected to one of the external leads 28 and 30 to the audio amplifier(not shown). The preferred construction is with both of the woven endleads 29 and 31 and the external leads 28 and 30 disposed atdiametrically opposed positions, the better to balance the weightcarried by the lower resilient support 40 and thus to avoid anyimbalance which may interfere with optimum operation of the speaker.

The loudspeaker illustrated in FIG. 3 is similar to that shown in FIGS.1 and 2, differing only in the magnet structure. While the magneticstructure of the FIGS. 1 and 2 embodiment utilizes a core of ceramicmaterial, that of FIG. 3 utilizes an Alnico core for pole piece 54.Mounted on this pole piece 54 are a pair of ferromagnetic arms 56,having the U-shaped configuration shown in the figure. Except at theirtops and bottoms arms 56 do not have the circular geometry of the FIGS.1 and 2 embodiment, and thus the air spaces 60 between parts 54 and 56are open to the surrounding atmosphere. At their upper ends the arms 56are necked down as shown, and an air gap 22 is provided between polepiece 54 and the inner ends of the connecting arms 56, corresponding tothe gap 22 in FIGS. 1 and 2. As in the previously described embodiment,this air gap contains the suspended coil form 32 having coil 24 tightlysecured thereon. In other respects, the structure 50 of the FIG. 3embodiment is the same as that previously described, and the sameidentifying numerals have been used to delineate its parts.

FIG. 4 illustrates another aspect of the present invention, acombination of one of the speakers previously described .with a primaryenclosure adapted to improve its response characteristics, in particularits omnidirectionality and its uniform loudness response to the entirefrequency spectrum. In this combination, as illustrated, one of theloudspeakers 10 shown in FIGS. 1 and 2 is shown mounted in an enclosure64 made of a hard material such as glass, Plexiglas, or other relativelyrigid plastic. The enclosure 64 is a sphere of anywhere from about 8inches in diameter on up, the larger the better. Its front end is openedto provide a mounting space for loudspeaker 50, and it is there providedwith a thickened lip 72 as shown to receive the mounting screws 73extending through the mounting holes in the speaker and threaded intotapped openings in the enclosure itself. At its opposite end, the sphereis provided with a second opening on which is mounted a removable cap63. The sphere is preferably sealed shut by the members mounted in theopenings, and connectors 65 are provided through cap 63. External leads66 and 67 are connected to these terminals on the outside, and on theinside relatively taut leads 68 and 69 connect the tenninals toterminals 26 of the loudspeaker, which connect internally to the ends ofthe voice coil, as previously described.

It should be mentioned, that the loudspeakers of the present inventionhave frequency responses and dispersion which are so good over theentire range of the audio frequency spectrum that they can be used toreplace all prior speakers, making the use of separate tweeters andwoofers obsolete. The preferred size range, in terms of the diameter ofdiaphragm 34, are from 2% up to 6 inches, and it should be rememberedthat in each case the diaphragm is buttressed and supported by theextended voice coil form to which it is rigidly secured. The entire massdiaphragm, voice coil form and voice coil are translated together as anentity, removing the prior disadvantage of speakers with largediaphragms, regardless of their configuration. This in itself is themajor contribution of the present inventor. Nevertheless, the auxiliaryimprovements should not be overlooked, namely the use of voice coilleads woven or otherwise secured to the lower resilient suspension andthe combination of the speakers with the primary enclosure in the formof a relatively rigid spherical shell.

What is claimed is:

1. In combination, a loudspeaker and a primary enclosure therefor, saidenclosure being of hard material and having the general form of aspherical shell, said loudspeaker being secured to the wall of saidenclosure at an opening therein, said loudspeaker comprising aframework, a magnet structure secured to one end of the framework andhaving an air gap therein, an outwardly convex diaphragm at the otherend of said framework with its outer edge resiliently supported thereby,a voice coil form secured to the center portion of said diaphragm on theconcave side thereof and extending down to said magnet structure andinto the air gap therein, a voice coil securely wound on the lower endof said form and disposed in said air gap, a second resilient supportextending between said framework and the voice coil form adjacent thevoice coil thereon, and lead wires from said voice coil to the outsideof the loudspeaker tightly secured to said second suspension.

2. The dynamic loudspeaker of claim 1 in which said outwardly convexdiaphragm is made of a metal and is between 2% and 6 inches in diameter.

3. A dynamic loudspeaker comprising a framework, a

magnet structure secured to one end of the framework and having an airgap as said end, an outwardly convex, rigid diaphragm disposed at theother end of said framework with its outer periph- 6 ery resilientlysupported thereon, a voice coil form having one end secured to thecenter portion of said diaphragm on the concave side thereof andextending to said magnet with its other end disposed in said air gap,and a voice coil securely mounted on said other end of the form and alsodisposed in said air gap. 4. The dynamic loudspeaker of claim 3 whichalso includes a second resilient suspension, said second resilientsuspension extending between said one end of the framework and saidvoice coil form from adjacent the voice coil thereon, and a pair of leadwires from the ends of said voice coil, said lead wires being tightlysecured to said second suspension.

5. A dyamic loudspeaker comprising a framework which includes a sidewalland an inwardly extending flange at one end, a magnetic structuresecured to said flange of the framework and having an annular slottherein forming an air gap, a dielectric tube and a voice coil wouldthereon disposed in said air gap, said dielectric tube projecting out ofsaid slot approximately to the outer end of said framework, a convexmetal diaphragm disposed at said outer end of the framework and securedthereto by an annularly corrugated resilient suspension permittinglimited reciprocating motion of the diaphragm along an axial line ofmotion coinciding with the axis of said tube, said diaphragm beingsecured to said projecting end of the tube adjacent the center of thediaphragm, so that all of the diaphragm, tube and voice coil reciprocatein unison, a second resilient suspension between said tube and saidframework adjacent but spaced from the secured end of the framework, anda pair of leads extending from the ends of said voice coil to theoutside of the framework. 6. In a moving coil loudspeaker of the typeordinarily employing a paper cone diaphragm having its large end securedto the large end of a conical framework by means of a first resilientsuspension and its small or apical end secured to both the moving coiland, by means of a second resilient suspension, to the small end of saidframework, the improvement comprising a convex metal diaphragm replacingsuch paper cone and disposed at such larger end of the framework, aresilient suspension supporting said convex metal diaphragm andconnecting it to the outer end of the framework, said moving coil beingtightly mounted on a form which projects above the coil and extends intocontact with the center portion of said metal diaphragm and is tightlysecured thereto, and a second resilient suspension secured to said formabove and adjacent the coil would thereon, the outer edge of the secondsuspension being secured to the small end of the framework.

1. In combination, a loudspeaker and a primary enclosure therefor, saidenclosure being of hard material and having the general form of aspherical shell, said loudspeaker being secured to the wall of saidenclosure at an opening therein, said loudspeaker comprising aframework, a magnet structure secured to one end of the framework andhaving an air gap therein, an outwardly convex diaphragm at the otherend of said framework with its outer edge resiliently supported thereby,a voice coil form secured to the center portion of said diaphragm on theconcave side thereof and extending down to said magnet structure andinto the air gap therein, a voice coil securely wound on the lower endof said form and disposed in said air gap, a second resilient supportextending between said framework and the voice coil form adjacent thevoice coil thereon, and lead wires from said voice coil to the outsideof the loudspeaker tightly secured to said second suspension.
 2. Thedynamic loudspeaker of claim 1 in which said outwardly convex diaphragmis made of a metal and is between 2 1/2 and 6 inches in diameter.
 3. Adynamic loudspeaker comprising a framework, a magnet structure securedto one end of the framework and having an air gap as said end, anoutwardly convex, rigid diaphragm disposed at the other end of saidframework with its outer periphery resiliently supported thereon, avoice coil form having one end secured to the center portion of saiddiaphragm on the concave side thereof and extending to said magnet withits other end disposed in said air gap, and a voice coil securelymounted on said other end of the form and also disposed in said air gap.4. The dynamic loudspeaker of claim 3 which also includes a secondresilient suspension, said second resilient suspension extending betweensaid one end of the framework and said voice coil form from adjacent thevoice coil thereon, and a pair of lead wires from the ends of said voicecoil, said lead wires being tightly secured to said second suspension.5. A dyamic loudspeaker comprising a framework which includes a sidewalland an inwardly extending flange at one end, a magnetic structuresecured to said flange of the framework and having an annular slottherein forming an air gap, a dielectric tube and a voice coil wouldthereon disposed in said air gap, said dielectric tube projecting out ofsaid slot approximately to the outer end of said framework, a convexmetal diaphragm disposed at said outer end of the framework and securedthereto by an annularly corrugated resilient suspension permittinglimited reciprocating motion of the diaphragm along an axial line ofmotion coinciding with the axis of said tube, said diaphragm beingsecured to said projecting end of the tube adjacent the center of thediaphragm, so that all of the diaphragm, tube and voice coil reciprocatein unison, a second resilient suspension between said tube and saidframework adjacent but spaced from the secured end of the framework, anda pair of leads extending from the ends of said voice coil to theoutside of the framework.
 6. In a moving coil loudspeaker of the typeordinarily employing a paper cone diaphragm having its large end securedto the large end of a conical framework by means of a first resilientsuspension and its small or apical end secured to both the moving coiland, by means of a second resilient suspension, to the small end of saidframework, the improvement comprising a convex metal diaphragm replacingsuch paper cone and disposed at such larger end of the framework, aresilient suspension supporting said convex metal diaphragm andconnecting it to the outer end of the framework, said moving coil beingtightly mounted on a form which projects above the coil and extends intocontact with the center portion of said metal diaphragm and is tightlysecured thereto, and a second resilient suspension secured to said formabove and adjacent the coil would thereon, the outer edge of the secondsuspension being secured to the small end of the framework.